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The
Institute for Inland water Management and Waste Water Treatment
(RIZA) is a governmental organization responsible for the
quality of surface and waste water in the Netherlands.
Analyzing
water with LC-MS(MS), a lot of unknown compounds are visible in the
chromatograms and it is very difficult to find their identity.
For EI large spectra libraries are available to assist in the
identification of unknown compounds. This is possible because
the EI spectra generated with different MS systems are
comparable both in fragment ions and ratios.
LC-MS/MS
spectra however differ widely. It is caused by the different ionization
methods, solvents, collision offset voltages etc. which can be applied. Comparing however the MS/MS spectra of
different ionization methods for a lot of compounds indicates,
that the fragment ions which are formed, most of the time have
the same m/z values, although the ratios differ widely.
Therefore
we started to build and the CI-CID library based on GC-CI-MS/MS,
LC-TSP-MS/MS and LC-APCI-MS/MS data. The GC-CI-MS/MS has been
used to ionize the standard compounds (about 400) of the GCMS
analysis we apply. Those library entries are very useful because
a lot of the compounds can also be seen by LC-MS/MS. A part of
the GC-CI-MS-MS spectra have been put into the library
Each
compound is analyzed at a range of collision offset voltages in
both the RFD and/or DAU scan mode. The m/z values of all
specific ions formed are put in the library entry at a ratio of
100 or 50% depending on the signal intensity of the fragment
ions during the whole collision offset range. Most of the
spectra generated by one of the other ionization methods
mentioned above can be found easily in the library.
By
sharing library entries of different labs via the internet, we
hope to increase the number of entries rapidly. Although our
interest is focused on compounds available in waste and surface
water the only limitation for the compounds which can be added
is a maximum molecular weight of about 1000.
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